The effort marks the first time EPA has invoked the Clean Water Act to address ocean acidification, and comes in response to a 2007 petition from the Center for Biological Diversity. The center noted that EPA has failed to update the pH standard since 1976 and has ignored research published since then.

Concerns about ocean acidification have risen lately, as research shows a link between it and rising atmospheric carbon dioxide levels. Studies show that oceans absorb about 22 million tons of CO2 per day from the atmosphere, resulting in increasing acidity that impairs marine animals' ability to build and maintain protective shells and skeletons and threatens coral reefs.

"The federal government has finally acknowledged that ocean acidification is a threat," she said in a statement. "Now it must take the next step and fully implement the Clean Water Act to protect our nation's waters from 'the other CO2 problem.'"

The center says EPA's recommended pH criterion is an important benchmark for states and tribes. A stricter recommendation could potentially help promote the imposition of federal CO2 controls.

The center also asked EPA to publish a guidance providing recommendations to states on preventing ocean acidification.

"We must take immediate action to address ocean acidification, or the impacts will be catastrophic," Sakashita said. "Fortunately, we need not wait for new legislation addressing CO2 emissions, as the Clean Water Act already provides us with important tools to confront this problem."

Stakeholders will have 60 days to submit ocean acidification data to the agency. EPA plans to decide whether the pH standards should be revised within one year.